#include "builtin.h"
#include "lockfile.h"
#include "commit.h"
#include "refs.h"
#include "dir.h"
#include "tree-walk.h"
#include "diff.h"
#include "revision.h"
#include "reachable.h"

/*
 * reflog expire
 */

static const char reflog_expire_usage[] =
"git reflog expire [--verbose] [--dry-run] [--stale-fix] [--expire=<time>] [--expire-unreachable=<time>] [--all] <refs>...";
static const char reflog_delete_usage[] =
"git reflog delete [--verbose] [--dry-run] [--rewrite] [--updateref] <refs>...";

static unsigned long default_reflog_expire;
static unsigned long default_reflog_expire_unreachable;

struct cmd_reflog_expire_cb {
        struct rev_info revs;
        int dry_run;
        int stalefix;
        int rewrite;
        int updateref;
        int verbose;
        unsigned long expire_total;
        unsigned long expire_unreachable;
        int recno;
};

struct expire_reflog_cb {
        FILE *newlog;
        enum {
                UE_NORMAL,
                UE_ALWAYS,
                UE_HEAD
        } unreachable_expire_kind;
        struct commit_list *mark_list;
        unsigned long mark_limit;
        struct cmd_reflog_expire_cb *cmd;
        unsigned char last_kept_sha1[20];
};

struct collected_reflog {
        unsigned char sha1[20];
        char reflog[FLEX_ARRAY];
};
struct collect_reflog_cb {
        struct collected_reflog **e;
        int alloc;
        int nr;
};

#define INCOMPLETE      (1u<<10)
#define STUDYING        (1u<<11)
#define REACHABLE       (1u<<12)

static int tree_is_complete(const unsigned char *sha1)
{
        struct tree_desc desc;
        struct name_entry entry;
        int complete;
        struct tree *tree;

        tree = lookup_tree(sha1);
        if (!tree)
                return 0;
        if (tree->object.flags & SEEN)
                return 1;
        if (tree->object.flags & INCOMPLETE)
                return 0;

        if (!tree->buffer) {
                enum object_type type;
                unsigned long size;
                void *data = read_sha1_file(sha1, &type, &size);
                if (!data) {
                        tree->object.flags |= INCOMPLETE;
                        return 0;
                }
                tree->buffer = data;
                tree->size = size;
        }
        init_tree_desc(&desc, tree->buffer, tree->size);
        complete = 1;
        while (tree_entry(&desc, &entry)) {
                if (!has_sha1_file(entry.sha1) ||
                    (S_ISDIR(entry.mode) && !tree_is_complete(entry.sha1))) {
                        tree->object.flags |= INCOMPLETE;
                        complete = 0;
                }
        }
        free_tree_buffer(tree);

        if (complete)
                tree->object.flags |= SEEN;
        return complete;
}

static int commit_is_complete(struct commit *commit)
{
        struct object_array study;
        struct object_array found;
        int is_incomplete = 0;
        int i;

        /* early return */
        if (commit->object.flags & SEEN)
                return 1;
        if (commit->object.flags & INCOMPLETE)
                return 0;
        /*
         * Find all commits that are reachable and are not marked as
         * SEEN.  Then make sure the trees and blobs contained are
         * complete.  After that, mark these commits also as SEEN.
         * If some of the objects that are needed to complete this
         * commit are missing, mark this commit as INCOMPLETE.
         */
        memset(&study, 0, sizeof(study));
        memset(&found, 0, sizeof(found));
        add_object_array(&commit->object, NULL, &study);
        add_object_array(&commit->object, NULL, &found);
        commit->object.flags |= STUDYING;
        while (study.nr) {
                struct commit *c;
                struct commit_list *parent;

                c = (struct commit *)study.objects[--study.nr].item;
                if (!c->object.parsed && !parse_object(c->object.sha1))
                        c->object.flags |= INCOMPLETE;

                if (c->object.flags & INCOMPLETE) {
                        is_incomplete = 1;
                        break;
                }
                else if (c->object.flags & SEEN)
                        continue;
                for (parent = c->parents; parent; parent = parent->next) {
                        struct commit *p = parent->item;
                        if (p->object.flags & STUDYING)
                                continue;
                        p->object.flags |= STUDYING;
                        add_object_array(&p->object, NULL, &study);
                        add_object_array(&p->object, NULL, &found);
                }
        }
        if (!is_incomplete) {
                /*
                 * make sure all commits in "found" array have all the
                 * necessary objects.
                 */
                for (i = 0; i < found.nr; i++) {
                        struct commit *c =
                                (struct commit *)found.objects[i].item;
                        if (!tree_is_complete(c->tree->object.sha1)) {
                                is_incomplete = 1;
                                c->object.flags |= INCOMPLETE;
                        }
                }
                if (!is_incomplete) {
                        /* mark all found commits as complete, iow SEEN */
                        for (i = 0; i < found.nr; i++)
                                found.objects[i].item->flags |= SEEN;
                }
        }
        /* clear flags from the objects we traversed */
        for (i = 0; i < found.nr; i++)
                found.objects[i].item->flags &= ~STUDYING;
        if (is_incomplete)
                commit->object.flags |= INCOMPLETE;
        else {
                /*
                 * If we come here, we have (1) traversed the ancestry chain
                 * from the "commit" until we reach SEEN commits (which are
                 * known to be complete), and (2) made sure that the commits
                 * encountered during the above traversal refer to trees that
                 * are complete.  Which means that we know *all* the commits
                 * we have seen during this process are complete.
                 */
                for (i = 0; i < found.nr; i++)
                        found.objects[i].item->flags |= SEEN;
        }
        /* free object arrays */
        free(study.objects);
        free(found.objects);
        return !is_incomplete;
}

static int keep_entry(struct commit **it, unsigned char *sha1)
{
        struct commit *commit;

        if (is_null_sha1(sha1))
                return 1;
        commit = lookup_commit_reference_gently(sha1, 1);
        if (!commit)
                return 0;

        /*
         * Make sure everything in this commit exists.
         *
         * We have walked all the objects reachable from the refs
         * and cache earlier.  The commits reachable by this commit
         * must meet SEEN commits -- and then we should mark them as
         * SEEN as well.
         */
        if (!commit_is_complete(commit))
                return 0;
        *it = commit;
        return 1;
}

/*
 * Starting from commits in the cb->mark_list, mark commits that are
 * reachable from them.  Stop the traversal at commits older than
 * the expire_limit and queue them back, so that the caller can call
 * us again to restart the traversal with longer expire_limit.
 */
static void mark_reachable(struct expire_reflog_cb *cb)
{
        struct commit *commit;
        struct commit_list *pending;
        unsigned long expire_limit = cb->mark_limit;
        struct commit_list *leftover = NULL;

        for (pending = cb->mark_list; pending; pending = pending->next)
                pending->item->object.flags &= ~REACHABLE;

        pending = cb->mark_list;
        while (pending) {
                struct commit_list *entry = pending;
                struct commit_list *parent;
                pending = entry->next;
                commit = entry->item;
                free(entry);
                if (commit->object.flags & REACHABLE)
                        continue;
                if (parse_commit(commit))
                        continue;
                commit->object.flags |= REACHABLE;
                if (commit->date < expire_limit) {
                        commit_list_insert(commit, &leftover);
                        continue;
                }
                commit->object.flags |= REACHABLE;
                parent = commit->parents;
                while (parent) {
                        commit = parent->item;
                        parent = parent->next;
                        if (commit->object.flags & REACHABLE)
                                continue;
                        commit_list_insert(commit, &pending);
                }
        }
        cb->mark_list = leftover;
}

static int unreachable(struct expire_reflog_cb *cb, struct commit *commit, unsigned char *sha1)
{
        /*
         * We may or may not have the commit yet - if not, look it
         * up using the supplied sha1.
         */
        if (!commit) {
                if (is_null_sha1(sha1))
                        return 0;

                commit = lookup_commit_reference_gently(sha1, 1);

                /* Not a commit -- keep it */
                if (!commit)
                        return 0;
        }

        /* Reachable from the current ref?  Don't prune. */
        if (commit->object.flags & REACHABLE)
                return 0;

        if (cb->mark_list && cb->mark_limit) {
                cb->mark_limit = 0; /* dig down to the root */
                mark_reachable(cb);
        }

        return !(commit->object.flags & REACHABLE);
}

/*
 * Return true iff the specified reflog entry should be expired.
 */
static int should_expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
                                    const char *email, unsigned long timestamp, int tz,
                                    const char *message, void *cb_data)
{
        struct expire_reflog_cb *cb = cb_data;
        struct commit *old, *new;

        if (timestamp < cb->cmd->expire_total)
                return 1;

        old = new = NULL;
        if (cb->cmd->stalefix &&
            (!keep_entry(&old, osha1) || !keep_entry(&new, nsha1)))
                return 1;

        if (timestamp < cb->cmd->expire_unreachable) {
                if (cb->unreachable_expire_kind == UE_ALWAYS)
                        return 1;
                if (unreachable(cb, old, osha1) || unreachable(cb, new, nsha1))
                        return 1;
        }

        if (cb->cmd->recno && --(cb->cmd->recno) == 0)
                return 1;

        return 0;
}

static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
                const char *email, unsigned long timestamp, int tz,
                const char *message, void *cb_data)
{
        struct expire_reflog_cb *cb = cb_data;

        if (cb->cmd->rewrite)
                osha1 = cb->last_kept_sha1;

        if (should_expire_reflog_ent(osha1, nsha1, email, timestamp, tz,
                                     message, cb_data)) {
                if (!cb->newlog)
                        printf("would prune %s", message);
                else if (cb->cmd->verbose)
                        printf("prune %s", message);
        } else {
                if (cb->newlog) {
                        char sign = (tz < 0) ? '-' : '+';
                        int zone = (tz < 0) ? (-tz) : tz;
                        fprintf(cb->newlog, "%s %s %s %lu %c%04d\t%s",
                                sha1_to_hex(osha1), sha1_to_hex(nsha1),
                                email, timestamp, sign, zone,
                                message);
                        hashcpy(cb->last_kept_sha1, nsha1);
                }
                if (cb->cmd->verbose)
                        printf("keep %s", message);
        }
        return 0;
}

static int push_tip_to_list(const char *refname, const unsigned char *sha1, int flags, void *cb_data)
{
        struct commit_list **list = cb_data;
        struct commit *tip_commit;
        if (flags & REF_ISSYMREF)
                return 0;
        tip_commit = lookup_commit_reference_gently(sha1, 1);
        if (!tip_commit)
                return 0;
        commit_list_insert(tip_commit, list);
        return 0;
}

static int expire_reflog(const char *refname, const unsigned char *sha1,
                         struct cmd_reflog_expire_cb *cmd)
{
        static struct lock_file reflog_lock;
        struct expire_reflog_cb cb;
        struct ref_lock *lock;
        char *log_file;
        struct commit *tip_commit;
        struct commit_list *tips;
        int status = 0;

        memset(&cb, 0, sizeof(cb));

        /*
         * The reflog file is locked by holding the lock on the
         * reference itself, plus we might need to update the
         * reference if --updateref was specified:
         */
        lock = lock_any_ref_for_update(refname, sha1, 0, NULL);
        if (!lock)
                return error("cannot lock ref '%s'", refname);
        if (!reflog_exists(refname)) {
                unlock_ref(lock);
                return 0;
        }

        log_file = git_pathdup("logs/%s", refname);
        if (!cmd->dry_run) {
                /*
                 * Even though holding $GIT_DIR/logs/$reflog.lock has
                 * no locking implications, we use the lock_file
                 * machinery here anyway because it does a lot of the
                 * work we need, including cleaning up if the program
                 * exits unexpectedly.
                 */
                if (hold_lock_file_for_update(&reflog_lock, log_file, 0) < 0) {
                        struct strbuf err = STRBUF_INIT;
                        unable_to_lock_message(log_file, errno, &err);
                        error("%s", err.buf);
                        strbuf_release(&err);
                        goto failure;
                }
                cb.newlog = fdopen_lock_file(&reflog_lock, "w");
                if (!cb.newlog) {
                        error("cannot fdopen %s (%s)",
                              reflog_lock.filename.buf, strerror(errno));
                        goto failure;
                }
        }

        cb.cmd = cmd;

        if (!cmd->expire_unreachable || !strcmp(refname, "HEAD")) {
                tip_commit = NULL;
                cb.unreachable_expire_kind = UE_HEAD;
        } else {
                tip_commit = lookup_commit_reference_gently(sha1, 1);
                if (!tip_commit)
                        cb.unreachable_expire_kind = UE_ALWAYS;
                else
                        cb.unreachable_expire_kind = UE_NORMAL;
        }

        if (cmd->expire_unreachable <= cmd->expire_total)
                cb.unreachable_expire_kind = UE_ALWAYS;

        cb.mark_list = NULL;
        tips = NULL;
        if (cb.unreachable_expire_kind != UE_ALWAYS) {
                if (cb.unreachable_expire_kind == UE_HEAD) {
                        struct commit_list *elem;
                        for_each_ref(push_tip_to_list, &tips);
                        for (elem = tips; elem; elem = elem->next)
                                commit_list_insert(elem->item, &cb.mark_list);
                } else {
                        commit_list_insert(tip_commit, &cb.mark_list);
                }
                cb.mark_limit = cmd->expire_total;
                mark_reachable(&cb);
        }

        for_each_reflog_ent(refname, expire_reflog_ent, &cb);

        if (cb.unreachable_expire_kind != UE_ALWAYS) {
                if (cb.unreachable_expire_kind == UE_HEAD) {
                        struct commit_list *elem;
                        for (elem = tips; elem; elem = elem->next)
                                clear_commit_marks(elem->item, REACHABLE);
                        free_commit_list(tips);
                } else {
                        clear_commit_marks(tip_commit, REACHABLE);
                }
        }

        if (cb.newlog) {
                if (close_lock_file(&reflog_lock)) {
                        status |= error("couldn't write %s: %s", log_file,
                                        strerror(errno));
                } else if (cmd->updateref &&
                        (write_in_full(lock->lock_fd,
                                sha1_to_hex(cb.last_kept_sha1), 40) != 40 ||
                         write_str_in_full(lock->lock_fd, "\n") != 1 ||
                         close_ref(lock) < 0)) {
                        status |= error("couldn't write %s",
                                        lock->lk->filename.buf);
                        rollback_lock_file(&reflog_lock);
                } else if (commit_lock_file(&reflog_lock)) {
                        status |= error("unable to commit reflog '%s' (%s)",
                                        log_file, strerror(errno));
                } else if (cmd->updateref && commit_ref(lock)) {
                        status |= error("couldn't set %s", lock->ref_name);
                }
        }
        free(log_file);
        unlock_ref(lock);
        return status;

 failure:
        rollback_lock_file(&reflog_lock);
        free(log_file);
        unlock_ref(lock);
        return -1;
}

static int collect_reflog(const char *ref, const unsigned char *sha1, int unused, void *cb_data)
{
        struct collected_reflog *e;
        struct collect_reflog_cb *cb = cb_data;
        size_t namelen = strlen(ref);

        e = xmalloc(sizeof(*e) + namelen + 1);
        hashcpy(e->sha1, sha1);
        memcpy(e->reflog, ref, namelen + 1);
        ALLOC_GROW(cb->e, cb->nr + 1, cb->alloc);
        cb->e[cb->nr++] = e;
        return 0;
}

static struct reflog_expire_cfg {
        struct reflog_expire_cfg *next;
        unsigned long expire_total;
        unsigned long expire_unreachable;
        size_t len;
        char pattern[FLEX_ARRAY];
} *reflog_expire_cfg, **reflog_expire_cfg_tail;

static struct reflog_expire_cfg *find_cfg_ent(const char *pattern, size_t len)
{
        struct reflog_expire_cfg *ent;

        if (!reflog_expire_cfg_tail)
                reflog_expire_cfg_tail = &reflog_expire_cfg;

        for (ent = reflog_expire_cfg; ent; ent = ent->next)
                if (ent->len == len &&
                    !memcmp(ent->pattern, pattern, len))
                        return ent;

        ent = xcalloc(1, (sizeof(*ent) + len));
        memcpy(ent->pattern, pattern, len);
        ent->len = len;
        *reflog_expire_cfg_tail = ent;
        reflog_expire_cfg_tail = &(ent->next);
        return ent;
}

static int parse_expire_cfg_value(const char *var, const char *value, unsigned long *expire)
{
        if (!value)
                return config_error_nonbool(var);
        if (parse_expiry_date(value, expire))
                return error(_("%s' for '%s' is not a valid timestamp"),
                             value, var);
        return 0;
}

/* expiry timer slot */
#define EXPIRE_TOTAL   01
#define EXPIRE_UNREACH 02

static int reflog_expire_config(const char *var, const char *value, void *cb)
{
        const char *pattern, *key;
        int pattern_len;
        unsigned long expire;
        int slot;
        struct reflog_expire_cfg *ent;

        if (parse_config_key(var, "gc", &pattern, &pattern_len, &key) < 0)
                return git_default_config(var, value, cb);

        if (!strcmp(key, "reflogexpire")) {
                slot = EXPIRE_TOTAL;
                if (parse_expire_cfg_value(var, value, &expire))
                        return -1;
        } else if (!strcmp(key, "reflogexpireunreachable")) {
                slot = EXPIRE_UNREACH;
                if (parse_expire_cfg_value(var, value, &expire))
                        return -1;
        } else
                return git_default_config(var, value, cb);

        if (!pattern) {
                switch (slot) {
                case EXPIRE_TOTAL:
                        default_reflog_expire = expire;
                        break;
                case EXPIRE_UNREACH:
                        default_reflog_expire_unreachable = expire;
                        break;
                }
                return 0;
        }

        ent = find_cfg_ent(pattern, pattern_len);
        if (!ent)
                return -1;
        switch (slot) {
        case EXPIRE_TOTAL:
                ent->expire_total = expire;
                break;
        case EXPIRE_UNREACH:
                ent->expire_unreachable = expire;
                break;
        }
        return 0;
}

static void set_reflog_expiry_param(struct cmd_reflog_expire_cb *cb, int slot, const char *ref)
{
        struct reflog_expire_cfg *ent;

        if (slot == (EXPIRE_TOTAL|EXPIRE_UNREACH))
                return; /* both given explicitly -- nothing to tweak */

        for (ent = reflog_expire_cfg; ent; ent = ent->next) {
                if (!wildmatch(ent->pattern, ref, 0, NULL)) {
                        if (!(slot & EXPIRE_TOTAL))
                                cb->expire_total = ent->expire_total;
                        if (!(slot & EXPIRE_UNREACH))
                                cb->expire_unreachable = ent->expire_unreachable;
                        return;
                }
        }

        /*
         * If unconfigured, make stash never expire
         */
        if (!strcmp(ref, "refs/stash")) {
                if (!(slot & EXPIRE_TOTAL))
                        cb->expire_total = 0;
                if (!(slot & EXPIRE_UNREACH))
                        cb->expire_unreachable = 0;
                return;
        }

        /* Nothing matched -- use the default value */
        if (!(slot & EXPIRE_TOTAL))
                cb->expire_total = default_reflog_expire;
        if (!(slot & EXPIRE_UNREACH))
                cb->expire_unreachable = default_reflog_expire_unreachable;
}

static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
{
        struct cmd_reflog_expire_cb cb;
        unsigned long now = time(NULL);
        int i, status, do_all;
        int explicit_expiry = 0;

        default_reflog_expire_unreachable = now - 30 * 24 * 3600;
        default_reflog_expire = now - 90 * 24 * 3600;
        git_config(reflog_expire_config, NULL);

        save_commit_buffer = 0;
        do_all = status = 0;
        memset(&cb, 0, sizeof(cb));

        cb.expire_total = default_reflog_expire;
        cb.expire_unreachable = default_reflog_expire_unreachable;

        for (i = 1; i < argc; i++) {
                const char *arg = argv[i];
                if (!strcmp(arg, "--dry-run") || !strcmp(arg, "-n"))
                        cb.dry_run = 1;
                else if (starts_with(arg, "--expire=")) {
                        if (parse_expiry_date(arg + 9, &cb.expire_total))
                                die(_("'%s' is not a valid timestamp"), arg);
                        explicit_expiry |= EXPIRE_TOTAL;
                }
                else if (starts_with(arg, "--expire-unreachable=")) {
                        if (parse_expiry_date(arg + 21, &cb.expire_unreachable))
                                die(_("'%s' is not a valid timestamp"), arg);
                        explicit_expiry |= EXPIRE_UNREACH;
                }
                else if (!strcmp(arg, "--stale-fix"))
                        cb.stalefix = 1;
                else if (!strcmp(arg, "--rewrite"))
                        cb.rewrite = 1;
                else if (!strcmp(arg, "--updateref"))
                        cb.updateref = 1;
                else if (!strcmp(arg, "--all"))
                        do_all = 1;
                else if (!strcmp(arg, "--verbose"))
                        cb.verbose = 1;
                else if (!strcmp(arg, "--")) {
                        i++;
                        break;
                }
                else if (arg[0] == '-')
                        usage(reflog_expire_usage);
                else
                        break;
        }

        /*
         * We can trust the commits and objects reachable from refs
         * even in older repository.  We cannot trust what's reachable
         * from reflog if the repository was pruned with older git.
         */
        if (cb.stalefix) {
                init_revisions(&cb.revs, prefix);
                if (cb.verbose)
                        printf("Marking reachable objects...");
                mark_reachable_objects(&cb.revs, 0, 0, NULL);
                if (cb.verbose)
                        putchar('\n');
        }

        if (do_all) {
                struct collect_reflog_cb collected;
                int i;

                memset(&collected, 0, sizeof(collected));
                for_each_reflog(collect_reflog, &collected);
                for (i = 0; i < collected.nr; i++) {
                        struct collected_reflog *e = collected.e[i];
                        set_reflog_expiry_param(&cb, explicit_expiry, e->reflog);
                        status |= expire_reflog(e->reflog, e->sha1, &cb);
                        free(e);
                }
                free(collected.e);
        }

        for (; i < argc; i++) {
                char *ref;
                unsigned char sha1[20];
                if (!dwim_log(argv[i], strlen(argv[i]), sha1, &ref)) {
                        status |= error("%s points nowhere!", argv[i]);
                        continue;
                }
                set_reflog_expiry_param(&cb, explicit_expiry, ref);
                status |= expire_reflog(ref, sha1, &cb);
        }
        return status;
}

static int count_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
                const char *email, unsigned long timestamp, int tz,
                const char *message, void *cb_data)
{
        struct cmd_reflog_expire_cb *cb = cb_data;
        if (!cb->expire_total || timestamp < cb->expire_total)
                cb->recno++;
        return 0;
}

static int cmd_reflog_delete(int argc, const char **argv, const char *prefix)
{
        struct cmd_reflog_expire_cb cb;
        int i, status = 0;

        memset(&cb, 0, sizeof(cb));

        for (i = 1; i < argc; i++) {
                const char *arg = argv[i];
                if (!strcmp(arg, "--dry-run") || !strcmp(arg, "-n"))
                        cb.dry_run = 1;
                else if (!strcmp(arg, "--rewrite"))
                        cb.rewrite = 1;
                else if (!strcmp(arg, "--updateref"))
                        cb.updateref = 1;
                else if (!strcmp(arg, "--verbose"))
                        cb.verbose = 1;
                else if (!strcmp(arg, "--")) {
                        i++;
                        break;
                }
                else if (arg[0] == '-')
                        usage(reflog_delete_usage);
                else
                        break;
        }

        if (argc - i < 1)
                return error("Nothing to delete?");

        for ( ; i < argc; i++) {
                const char *spec = strstr(argv[i], "@{");
                unsigned char sha1[20];
                char *ep, *ref;
                int recno;

                if (!spec) {
                        status |= error("Not a reflog: %s", argv[i]);
                        continue;
                }

                if (!dwim_log(argv[i], spec - argv[i], sha1, &ref)) {
                        status |= error("no reflog for '%s'", argv[i]);
                        continue;
                }

                recno = strtoul(spec + 2, &ep, 10);
                if (*ep == '}') {
                        cb.recno = -recno;
                        for_each_reflog_ent(ref, count_reflog_ent, &cb);
                } else {
                        cb.expire_total = approxidate(spec + 2);
                        for_each_reflog_ent(ref, count_reflog_ent, &cb);
                        cb.expire_total = 0;
                }

                status |= expire_reflog(ref, sha1, &cb);
                free(ref);
        }
        return status;
}

/*
 * main "reflog"
 */

static const char reflog_usage[] =
"git reflog [ show | expire | delete ]";

int cmd_reflog(int argc, const char **argv, const char *prefix)
{
        if (argc > 1 && !strcmp(argv[1], "-h"))
                usage(reflog_usage);

        /* With no command, we default to showing it. */
        if (argc < 2 || *argv[1] == '-')
                return cmd_log_reflog(argc, argv, prefix);

        if (!strcmp(argv[1], "show"))
                return cmd_log_reflog(argc - 1, argv + 1, prefix);

        if (!strcmp(argv[1], "expire"))
                return cmd_reflog_expire(argc - 1, argv + 1, prefix);

        if (!strcmp(argv[1], "delete"))
                return cmd_reflog_delete(argc - 1, argv + 1, prefix);

        return cmd_log_reflog(argc, argv, prefix);
}